Remote identification system



United States Patent O "ice US. Cl. 340-412 6 Claims ABSTRACT OF THEDISCLOSURE A remote identification system comprises a plurality ofelectronic relay circuits each capable upon actuation of causing theflow of a similar increment of current. The relay circuits are coupledeach to the next in a series such that actuation of any one of the relaycircuits causes the actuation of the next following relay circuit of theseries. There are also a plurality of detectors each associated with andcoupled electrically to a respective one of the relay circuits foractuation thereof when the associated detector operates, a commonconductor connected to all of the relay circuits, There is acurrent-amplitude re sponsive device connected to the common conductorfor indicating the sum total of the increments of current caused to flowin the common conductor as a result of actuation of any one relaycircuit by its associated detector with resultant actuation of the otherfollowing relay circuits of the series.

This application is a continuation-in-part of my copending application,Ser. No. 406,388, filed Oct. 26, 1964.

The present invention relates to means for identification from adistance, and has as its object the provision of a method and anapparatus by means of which it is possible to monitor the operation of,and to identify, a supervisory detector belonging to a network ofautomatic monitoring and alarm devices adapted to respond to externalstimula tions produced by any appropriate physical, chemical orphysico-chemical agent.

By way of non-limiting example, there may be mentioned the applicationof the apparatus to fire detection or to the combination of a network offire detectors with proximity (anti-theft) detectors, means fordetecting the opening and closing of doors and, in general, anyapparatus whose essential function is to provide an alarm, to triggercounter-measure systems or automatic prevention devices.

In British patent specification No. 1,081,974 the applicants havedescribed a method and an apparatus which achieve this result. Thismethod consists essentially in providing a pulse generator inassociation with each detector of the network, in placing the outputcircuits of these generators in series by connecting them to a devicesituated at a central station, so that when one of the generators emitsa pulse as a result of the operation of the detector with which it isassociated, this pulse brings about the operation of the succeedinggenerator, whereby there 3,503,067 Patented Mar. 24, 1970 that one ofthe pulse generators employed does not return These objects are achievedby providing a constant-current generator in association with each ofthe detectors of a network, by connecting the outputs of the generatorsin such manner as to collect, in a line terminated at the centralstation by an appropriate indicating device, the sum of the currentsemitted by the sequentially actuated generators, whereby it is possibleto identify the generator from which the summation started, i.e. toidentify the generator and thus the detector which were the first tooperate.

It will be seen that a system comprising the two variants of the methodof location by pulse counting and by summation of the currents avoidsthe aforesaid objections to the said earlier system referred to, becausethe indicating system of this invention will continue to give anindication, when the installation is returned into service, in the eventof one of the generators not having returned to its initial state inwhich it transmits no current.

On the other hand, it is possible by reading the indicating device ofthe new system to verify whether the count read at the pulse generatoris correct. Any discrepancy between the readings of the indicatingdevice and of the counter will reveral state of disturbance.

By using only the second variant involving the summation of thecurrents, it is possible to provide a simple installation which may besufficient in many cases, although it does not exert any duplicatemonitoring as indicated above.

FIGURE 1 of the accompanying drawing is a circuit diagram having anetwork of detectors arranged according to the invention. A series ofsignal generators 2A, 2B, 2N are provided each in association with arespective one of a series of detectors 1A, 1B, IN. The signalgenerators are so arranged that the operation of one of them actuatesthe succeeding generator, and so on, in cascade, up to the last one.Each actuated generator transmits a signal along the line 4.

In accordance with the present improvement, the generators 2A, 2B, 2Nsupply constant current. These generators may be of any type known perse, for example of the type comprising thyratrons, semiconductors, etc.

Each time one of these generators is actuated, it feeds and continues tofeed a constant-current signal along the line 4, so that the strength ofthe current flowing through the line 4 is equal to the sum of thecurrents emitted by all of the generators which happen to have beensequentially actuated. If I is the current of a generator and m thenumber of sequentially actuated generators, the current strength alongthe line 4 will be mI. This strength, which is measured on a measuringinstrument 5, e.g. an ammeter, therefore determines the number ofgenerators which have been actuated in the network, and thus identifiesthe detector which has produced the alarm. Thus, if the detector 1Aoperators, for example as a result of the appearance of smoke revealingthe commencement of a fire, it actuates the generator 2A associatedtherewith. This generator transmits a constant-current signal I alongthe line 4 and energizes.

the succeeding generator 2B through the link 3. The generator 2B in turntransmits a signal I along the line 4 and energises the succeedinggenerator 2C, and so on until the last generator 2N has operated andemitted a i signal I. There will thus have been set up along the line 4a signal current of amplitude NI which is measured at the indicatingdevice 5. The latter may be a milliammeter or an ammeter, optionallygraduated in numbers of detectors, or again an electronic voltmeter oreven both when the number of detectors installed is large; themilliammeter may then give a coarse indication (tens, hundreds, forexample) and the electronic voltmeter a precise indication in thisrange.

In the system thus constructed, it will be seen that when the network ofdetectors is returned into service from the central station by a devicesuch as that described in the aforementioned patent, if a detector doesnot return to its initial state the generator associated therewith willcontinue to supply a signal I along the line 4, so that a reading willcontinue to be present at the device 5 and the operator may immediatelydetect the defect. If, for example,.the detector 1B does not return toits initial state, the generator 2B emit its signal I and energises thegenerator 2C, as described in the foregoing, and so on. In this case,the device 5 identifies the detector 1B by the number N-1, since (N-l)generators have remained in circuit.

This system therefore affords complete security. On the other hand, ifit is combined with a counting device, as diagrammatically illustratedat 7, it will be appreciated that the device 5 makes it possible tocheck the readings of the counter, whereby the reliability of the systemis doubled.

Referring now to FIGURE 2 D1, D2, D3 Drz are a series of detectorsarranged in such a manner that when one of these detector becomesoperative, an electrical current issued from a battery B flows throughtheir corresponding resistors R1, R2, R3 Rn. All detectors D areconnected in such a manner that when one of them becomes operative, itrenders the device next to it in the series operative, and so on alongthe series.

This means that through meter M there will flow a current which isequalto the current of one detector multiplied by the number of operativedetectors and the reading of meter M will therefore permit theidentification of the device which was first to operate.

For example, if there are twenty detectors, such as D1, D2, Dn, thenwhen one of them is operative, a current of ten milliamps flows acrosseach resistor R1, R2, Rn.

It is obvious that if the detector which is twelfth in the seriesmeasured from the meter end is rendered operative, the eleven detectorsfollowing it will also be rendered operative, so that meter M willdefiect to 120 milliamps, and that reading is specific to the twelfthdetector, which is accordingly indicated to the user.

The detectors may include, for example, relays in a sequentialdistribution, or valves, silicon controlled rectifiers, thyratrons, (hotor cold) and transistors. In fact any controllable device capable ofdelivering a predetermined amount of electrical current can be used.

FIGURE 3 shows a preferred Way of carrying out the invention with theuse of silicon controlled rectifiers or solid state thyratrons.

In this case D1, D2, D3, Dn, are detectors in the form of sensingelements designed in such a manner that they can provide enough power toactuate the corresponding silicon controlled rectifiers, Q1, Q2, Q3, Qn,which are cathode loaded by resistors R1, R2, R3, Rn.

It is presumed that all the silicon controlled rectifiers are identicaland that all the loading resistors are identical.

If one of the detector-sensing elements actuates its rectifier, the nextsensing element is excited and also actuates its rectifier, and so on tothe last rectifier of the chain, in the direction towards the meter M.

Therefore each of the operative silicon controlled rectifiers willprovide meter M with a current which is identical for each unit andtherefore the current across M will be the sum of the currents of allthose devices which have become operative.

Accordingly, the reading of M will permit immediate location of theinitially operated detector.

In practice, detectors D1, D2, D3, Dn, may be any suitable type ofdetecting element and Q1, Q2,'Q3, Qn may be any suitable type of siliconcontrolled rectifier or thyristor or any electrical or electronicbistable device (on-off) while R is essentially defined by the value ofthe full scale deflection ofthe pointer of M divided by the number ofdetecting units.

It will be obvious that the solution afforded by the invention of thepresent application, when employed alone, is reliable since it is notattended by the previously mentioned disadvantage, and economical, sinceit only involves the use of a simple and inexpensive measuring device.This solution is ideal in cases where double safety is not required.

I claim:

1. A remote identification system comprising a plurality of electroniccircuit means each capable upon actuation of causing the flow of asimilar increment of current, said plurality of means being coupled eachto the next in a series such that actuation of any of one of saidcircuit means causes the actuation of the next following circuit meansof the series, a plurality of condition sensing means each associatedwith and coupled electrically to a respective one of said circuit meansfor actuation thereof when the associated condition sensing meansoperates, a common conductor connected to all of the circuit means, anda current-amplitude responsive means connected to said common conductorfor indicating the sum total of the increments of current caused to flowin the common conductor as a result of actuation of any of one circuitmeans by its associated condition sensing means with resultant actuationof all of the other following circuit means of the series.

2. A remote identification system, as claimed in claim 1, wherein eachcircuit means has a respective impedance in series therewith, theplurality of circuit means being all coupled in parallel across acurrent source.

3. A remote identification system, as claimed in claim 2, wherein thecircuit means are thyratrons.

4. A remote identification system, as claimed in claim 2, wherein thecircuit means are semiconductor devices.

5. A remote identification system, as claimed in claim 1, wherein thecurrent-value indicating device is an ammeter.

6. In combination, a remote identification system as claimed in claim 1,and a counter means connected to said common conductor and arranged tocount the number of incremental changes of current value resulting fromactuation of any one circuit means by its associated condition sensingmeans with resultant actuation of the other following circuit means ofthe series.

References Cited UNITED STATES PATENTS 3,147,464 9/1964. Spielman340--213.1 3,047,843 7/1962 Katz 34O2l3 3,109,929 11/1963 Picard 340-2133,245,066 4/1966 Maffiet 340-213 FOREIGN PATENTS 923,744 4/1963 GreatBritain.

THOMAS B. HABECKER, Primary Examiner US. Cl. X.R. 307252; 34O 359

